Interfacial Chemistry in Al/CuO Reactive Nanomaterial and Its Role in Exothermic Reaction.

Interface layers between reactive and energetic materials in nanolaminates or nanoenergetic materials are believed to play a crucial role in the properties of nanoenergetic systems. Typically, in the case of Metastable Interstitial Composite nanolaminates, the interface layer between the metal and oxide controls the onset reaction temperature, reaction kinetics, and stability at low temperature. So far, the formation of these interfacial layers is not well understood for lack of in situ characterization, leading to a poor control of important properties. We have combined in situ infrared spectroscopy and ex situ X-ray photoelectron spectroscopy, differential scanning calorimetry, and high resolution transmission electron microscopy, in conjunction with firstprinciples calculations to identify the stable configurations that can occur at the interface and determine the kinetic barriers for their formation. We find that (i) an interface layer formed during physical deposition of aluminum is composed of a mixture of Cu, O, and Al through Al penetration into CuO and constitutes a poor diffusion barrier (i.e., with spurious exothermic reactions at lower temperature), and in contrast, (ii) atomic layer deposition (ALD) of alumina layers using trimethylaluminum (TMA)produces a conformal coating that effectively prevents Al diffusion even for ultrathin layer thicknesses (∼0.5 nm), resulting in better stability at low temperature and reduced reactivity. Importantly, the initial reaction of TMA with CuO leads to the extraction of oxygen from CuO to form an amorphous interfacial layer that is an important component for superior protection properties of the interface and is responsible for the high system stability. Thus, while Al e-beam evaporation and ALD growth of an alumina layer on CuO both lead to CuO reduction, the mechanism for oxygen removal is different, directly affecting the resistance to Al diffusion. This work reveals that it is the nature of the monolayer interface between CuO and alumina/Al rather than the thickness of the alumina layer that controls the kinetics of Al diffusion, underscoring the importance of the chemical bonding at the interface in these energetic materials

Noise Amplification in Human Tumor Suppression following Gamma Irradiation

The influence of noise on oscillatory motion is a subject of permanent interest, both for fundamental and practical reasons. Cells respond properly to external stimuli by using noisy systems. We have clarified the effect of intrinsic noise on the dynamics in the human cancer cells following gamma irradiation. It is shown that the large amplification and increasing mutual information with delay are due to coherence resonance. Furthermore, frequency domain analysis is used to study the mechanisms

Gene switching rate determines response to extrinsic perturbations in the self-activation transcriptional network motif

International audienc

Historical Perspective and Contribution of US Researchers into the Field of Self-Propagating High-Temperature Synthesis (SHS)/Combustion Synthesis (CS): Personal Reflections

In 1967, Merzhanov, Skhiro, and Borovinskaya published the first comprehensive paper describing self-sustaining character of reactions in a condensed phase, which could be utilized for synthesis of many ceramic and intermetallic materials [1]. In this paper, the authors demonstrated the principle of the so called “solid flame” using reactions between transition metals and boron, carbon or nitrogen. The world-wide combustion synthesis community considers this comprehensive paper and subsequent integrated experimental and theoretical research effort conducted in the former Soviet Union as the beginning of a new approach and method of synthesizing advanced high temperature materials. The main research was conducted by many Russian scientists at the Branch of Russian Academy of Sciences in Chernogolovka under the leadership of Professors Merzhanov and Borovinskaya [2–11]. During that period of our history, free exchange of information among scientists from different countries was very limited due to the cold war. The main source of information on research discoveries and accomplishments of Russian scientists available to US and other researchers was through publications in Russian journals or their translated versions. Such as Combustion, Explosion, and Shock Waves, Doklady Academy Nauk SSSR, Soviet Powder Metallurgy of Metals and Ceramics, Inorganic Materials, and Doklady Physical Chemistry were the most searched journals in the area of combustion synthesis. In the early 90s, a new International Journal of Self-Propagating High-Temperature Synthesis was created and it is published quarterly since its inception. Self-propagating high-temperature synthesis (SHS) also called combustion synthesis (CS) is the exothermic process in which the reaction between two or more solid reactants or gas and condensed reactants takes place in a self-sustaining regime leading to the formation of solid products of a higher value [12–14]. During the past forty years, hundreds of different compounds, including, nitrides, borides, carbides, silicides, sulfides, phosphides, hydrides, and oxides of many elements as well as intermetallics, composites, nonstoichiometric compounds, and solid solutions were successfully synthesized by this method [12–18]. Some materials have been successfully scaled-up and produced by the industry. To this group of materials among others belong: carbides of titanium, zirconium, tungsten, tantalum, boron and silicon, titanium diboride, molybdenum disilicide, aluminum nitride, silicon nitride, nickel aluminides, titanium nickelide, zirconium aluminides, and a number of composites (e.g. TiC–TiB2 and SiC–Si3 N4) or solid solutions such as SIALONs and aluminum oxynitride (ALON)

Energia aktywacji pęcznienia drewna buka (Fagus sylvatica L.) w wodzie

The activation energy of swelling beech wood (Fagus sylvatica L.) in water. This paper shows the results of the activation energy of swelling beech wood in water. The results showed that activation energy depends on the density. Increasing that values increase activation energy of swelling.Energia aktywacji pęcznienia drewna buka (Fagus sylvatica L.) w wodzie. W pracy przedstawiono wyniki oznaczeń energii aktywacji procesu pęcznienia drewna w wodzie. Uzyskane rezultaty wykazały, że wartość tej wielkości zależy od gęstości. Wraz ze wzrostem gęstości drewna buka wzrasta energia aktywacji jego pęcznienia

Energia aktywacji pęcznienia bielastego drewna sosny (Pinus sylvestris L.) w wodzie

The activation energy of swelling sap of pine wood (Pinus sylvestris L.) in water. This paper shows the results of the activation energy of swelling sapwood of pine wood in water. The results showed that activation energy value range from 4.8 to 10.7 kJ/mol. It is also noted that its depend on the density.Energia aktywacji pęcznienia bielastego drewna sosny (Pinus sylvestris L.) w wodzie. W pracy przedstawiono wyniki oznaczeń energii aktywacji procesu pęcznienia bielu drewna sosny zwyczajnej w wodzie. Uzyskane rezultaty wykazały, że wartość tej energii mieści się w przedziale od 4,8 do 10,7 kJ/mol i jest słabo zależna od gęstości drewna